9
Visceral Leishmaniasis (VL)
In VL, amastigotes (the tissue stage of the parasite) disseminate throughout the
reticuloendothelial system and occasionally are found in other organ systems.
17. The Panel recommends the collection of tissue aspirates or biopsy
specimens for smears, histopathology, parasite culture, and
molecular testing (S-L).
18. Bone marrow aspiration is the preferred first source of a diagnostic
sample. Liver, enlarged lymph nodes, and whole blood (buffy coat)
are other potential sources of tissue specimens (S-L).
19. Serum should be collected for detection of antileishmanial
antibodies (see Recs. 9, 21, 22) (S-M).
20. In immunocompromised persons, blood should be collected for buffy
coat examination, in vitro culture, and molecular analyses (S-VL).
21. Serologic testing is recommended for persons with suspected VL
in whom definitive diagnostic tests for the parasite (microscopic
identification, culture, and molecular tests for parasite DNA) cannot
be conducted or have negative results (S-M).
• The sensitivity and specificity of serologic tests depend on the assay and antigens
used, as well as host factors. Serologic tests cannot be used to assess the response
to treatment.
• Antileishmanial antibodies can be detected years after clinically successful
therapy in some persons.
22. The Panel suggests that tests for antileishmanial antibodies NOT be
performed as the sole diagnostic assay. (W-L)
• Antibodies may be undetectable or present at low levels in persons with VL who
are immunocompromised because of concurrent HIV/AIDS or other reasons.
The potential for false-negative test results limits the utility of serologic assays in
this setting.
